UNITED STATES - DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY LIBRARY LUNAR _JEXAS 77058 This report is preliminary and has not been edited or reviewed for conformity with U.S. Geological Survey standards and nomenclature. Prepared by the Geological Survey for the National Aeronautics and Space Administration INTERAGENCY REPORT: ASTROGEOLOGY 46 APOLLO 16 (DESCARTES) LANDING SITE ROAD LOG by E. L. Boudette, J. P. Schafer, and D. P. Elston April 1972 This report concerns work done on behalf of the National Aeronautics and Space Administration Manned Spacecraft Genter, Houston, Texas NASA Contract T-5874-A CONTENTS page EVA I. 1 EVA II 4 EVA III 12 iii APOLLO 16 (DESCARTES) LANDING SITE ROAD LOG l/ 2/ by E. L. Baudette, J. P. Schafer, and D. P. Elston EVA I 0.0 KM Leave ALSEP area on azimuth 280°; distance to Station 1 is Drive over undulating terrain of irregular unit of the Cayley Formation with degraded craters up to about 50 m across. 0.3 Cross northeast-trending filigree (possible layering) shown by low, sinuous escarpment. 0.8 Area of Station 2, North Rim of Spook (degraded crater) Convex escarpment about 5 m high facing southeast, which may require slight detour to north. Boulders ~s m l/This road log is intended for use with the following materials: (a) U. S. Geological Survey, 1972, Apollo 16 (Descartes) Sur- face Data Package (1:12,500 and 1:25,000-scale maps): [unpublished]. (b) Baudette, E. L., Schafer, J. P., and Elston, D. P., 1972, Engineering geology of the Apollo 16 (Descartes) traverse area (1~12,500-scale): U.S. Geol. Survey Open File Map, April 1972. (c) Elston, D.P., Baudette, E. L., and Schafer, J.P., 1972, Geologic map of the Apollo 16 (Descartes) landing site area (1:25,000-scalef. u.s. Geol. Survey Open File Map, April 1972. ~/Station tasks and procedures are not given. See other sources such as cuff check lists and traverse planning kits. 1 across appear to northwest in direction of Buster and possibly athwart path. Layering (bench and step topogra- phy) or colluvial features may be present in Spooke 0.9 Leave area of Station 2 on azimuth ~270° Small (~30 m), sharp secondary craters about 100 m ahead and to the southwest. Buster Crater is within a block field ~l50 m to northwest. A convex escarpment trending to northeast, east of Halfway Crater, may provide a bedrock sampling target. 1.3 West of Halfway Crater Ma.jor escarpment and crease with up to 20 m of relief lies athwart traverse and may require detour to the south. Traverse here is over undulating, cratered, locally block- covered terrain. Largest blocks are associated with 30- 40 m secondary craters. 1.5 Station 1 (east rim of Flag) Plum Crater is to southwest on edge of Flag's rim and continuous ejecta blanket, about 40 m across at this point. Boulders in the area are probably a mixed suite contributed from North Ray and South Ray Craters, and perhaps local sources. Layering and colluvial features are possible in Flag Crater. Ray material (light albedo) from South Ray is abundant east and west of Flag. Return by same route to Station 2, then to Station 3 which is 50 m west of LM site. 2 2.9 Station 3 Regolith here appears to be darker, representing different underlying unit than in areas of Flag and Spook craters. Area is comparatively free from South Ray contri- bution that was seen to west. An albedo contrast appears to mark the contact. 3 EVA II 0.0 KM Leave LM Site on azimuth ~173°; distance to Station 4 is 4.4 km Route south to Survey Ridge is over rolling irregular terrain. Pronounced ray material is nearly absent over the route, which has low albedo. The northern two-thirds of this traverse leg is lightly cratered; the southern third is among several 20-40 m craters both sharp and degraded. Mounds that occur northeast of Phantom Crater may be vol- canic constructional features. Filigree,shown by albedo stripes on the crest of Survey Ridge, is interpreted to be primary layering in volcanic rocks. Outcrops may be found in areas where the filigree is well-developed. The immediate approach to Survey Ridge is over a bright patch of regolith believed to be strewn by a block swarm from South Ray. Abundant relatively small blocks, and possibly an ejecta mantle, occur near the crest of the ridg~. 1.3 Traverse crest of Survey Ridge on azimuth 227° Blocks of varied lithologic types may occur along the ridge crest which is mantled by light regolith. Northeast- trending convex scarps facing southeast bound the ridge. The slope of Stone Mountain to the south appears to be held up by two major stratigraphic units comprised of probable lava flows. The major units are recognized on the basis of topographic benches, albedo, and surface morphology. The 4 lower unit is light medium gray with a relatively smooth surface, and the upper unit is dark medium gray and rougher appearing. The best development of filigree occurs to the southeast of Stone Mountain, associated with lobate scarps. This filigree may reflect primary layering. 1.7 Leave Survey Ridge on azimuth ~168° The traverse from the ridge for a distance of about 1.4 km is over a lightly cratered terrain characterized by patches of high albedo dispersed over a regolith of low background albedo. These patcheq are probably produced by the same process which affected the ridge crest, therefore blocks from South Ray are probably abundant. The latter one-third of this traverse leg in the direction of the major morphologic boundary at the base of Stone Mountain is over rather dark regolith. Some large blocks are associated with small 25-35 m craters. The approach to Stone Mountain is over a transitional unit (Idd ) between rocks of the 0 Cayley Formation (lei) and materials of the Descartes Mountains. Albedo contrasts and low scarps or subtle topo- graphic breaks may be apparent on the ground which define the contact. Filigree occurs ahead and to the southeast, with possible associated outcrops. 2.7 Turn right to azimuth 191° Route is between two rather fresh, probable secondary craters; blocks are resolvable within or on their rims. 5 The regolith appears dark. A convex escarpment or change in albedo of regolith about 70 m south of the southern cra- ter indicates a possible change in subsurface materials. South of the contact, filigree is common. The following hypotheses to explain the origin of filigree seen on the photographs need to be evaluated: 1. An optical or photographic phenomenon. 2. Colluvial (regolith) flow patterns. 3. Relief resulting from near-surface layered bedrock forming benches draped by regolith. Outcrops should occur locally. 4. Some combination of the above. Station 6 bypass; turn left to azimuth 161° Slope on Stone Mountain increases up to about 10° ne&r the contact between Idd and Idd , where regolith becomes 0 1 darker and is sparsely cratered. The thickest regolith may occur at the base of the mountain, related to mass wastage on the slopes above. A relatively rapid destruction of small craters by colluvial transport may occur here, 3.5 Station 5 bypass; turn right to azimuth 176° Traverse is along the base of the upper and most pro= minent Stone Mountqin bench held up by unit Idd • A dis- 2 tinct albedo contrast between the principal units may be visible on the ground here. Outcrops may occur on the steep pitch. A view west into Stubby occurs at end of traverse leg. 6 3.9 200 m west of Cinco Craters; turn left to azimuth 132° The slopes increases to ~12°-15° where trafficability may become fairly difficult. The surface becomes smoother after ~zoo m, although crater density, block density, and block size increase. Regolith thickness may decrease up- ward on slope. The filigree here may or may not compare to that on lower slopes. 4.4 Station 4 (Cinco Craters d and e); depart on azimuth ~331° A west to north panorama of Descartes landing site area may be seen from here. This area provides the only opportunity to see simultaneously into several craters in the southern part of the landing area. The walls of South Ray, Baby Ray, Stubby, and Wreck are of particular interest. Large scale geomorphic features of Smoky Mountain can be observed from here also. Boulders about 10-20 m across, probably from South Ray, occur about 50 m to south on the rim of Cinco e. Cinco d and e craters appear to penetrate the regolith, believed to be thin, and should provide an oppor- tunity to sample locally derived Descartes materials. The return to Station 5 is scheduled to cross terrain east of Cinco a, b, and c. The appearance of filigree, blocks, and albedo contrasts may be enhanced in different sun angle, and regolith thickness may be easier to estimate. 5.2 Station 5; depart on azimuth 341° Observations made near Station 5 on bypass traverse 7 leg may be helpful in explaining the prominent step and bench topography here. Station 5 appears to be just above the base of a regional sub-unit of the Descartes (Idd ). 2 The lithologic contrasts between the sub-units of the Descartes materials (Idd and Idd ), as well as with the 2 1 Cayley Formation at the base of Stone Mountain,may be dis- tinctive and thus reflected in the regolith. Retrace traverse bypass leg to Station 6. 5.6 Station 6; depart on azimuth ~239° Station 6 is near the contact between Idd and the 1 transitional unit, Idd • The route to Station 7 approaches 0 the rim of Stubby Crater over sparsely cratered terrain with irregular ejecta from South Ray and regolith strewn by block swarm debris.